Plasma torches have been used for many years for cutting shapes from sheets of metal materials. Handheld plasma torches have been developed for quickly and efficiently cutting shapes from materials. While efficient in cutting material, handheld torches are limited in their accuracy to the skill of the operator. Some parts, such as those for artistic works may not need to be accurate. Other parts, such as those used in mechanical devices, often need to meet certain tolerances and need extreme accuracy. Extreme accuracy is not possible with a manually operated handheld plasma torch.
To overcome this problem, plasma torches have been developed which are designed specifically to be mounted to machines capable of controlling the torches horizontally along an x axis and a y axis. These machines can be programmed to cut shapes by inputting a system of coordinates. They can be highly accurate and produce identical parts. There are, however, a number of problems with these devices. Operation of these systems is very complex, requiring extensive training, programming of the device can be very time consuming, and small changes require reworking of the entire program. The systems are expensive and the torches themselves are more costly than the handheld torches. These problems reduce the economic gains achieved by having an automated system performing the cuts.
Other problems include accuracy and efficiency. While cutting a planar sheet of material would appear to require only movement of the torch horizontally along an x axis and a y axis, the sheets being cut may not be absolutely planar, or more likely, upon cutting, the heat generated can cause buckling of the material. As the cutting torch moves over the surface of the material, these irregularities can result in changes in the distance between the tip of the torch and the surface being cut. The changes in distance can adversely affect the accuracy of the cut. Furthermore, pressure on the tip can cause damage thereto or result in a stoppage. All of these problems can be costly in time, accuracy and money.
Height control of the plasma nozzle or torch above the work helps with plasma cutting because material is never perfectly flat and because the work generally warps when cutting. Plasma cutters work best when the distance of the plasma torch above the work is regulated and tightly controlled. Some early cutting machines or systems didn't include a height control at all. Some early cutting machines or systems used a height control that involved actually dragging the torch tip or nozzle across the material. The dragging action can lead to the torch hanging up more, and consumables wearing out more as compared to a strategy involving a floating height above the material.
In one prior art system, the plasma cutter simply starts moving a preset time delay after it fires the trigger of the plasma torch. This method leads to malfunctions any time the plasma torch takes more or less time to start the cut than expected. This method also causes malfunctions if the plasma torch isn't working at all, because the machine still tries to cut—not knowing that the torch isn't cutting.
Another prior art cutting system requires a special plasma torch (or cutter) with an additional relay and a pair of wires from the torch. The relay in the torch switches when cutting has transferred to the work piece. Plasma cutting systems using this method may begin cutting motion and also activate a height control after detecting that the relay has closed.
Many of these problems were solved by an improved cutting machine disclosed in U.S. Pat. No. 6,218,639, issued 17 Apr. 2001 and incorporated herein by reference. However, some of the problems, such as height control, or control of the cutting torch above the work, can still be a problem in certain applications.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object the present invention to provide new and improved cutting system controls.
Another object of the present invention is to provide new and improved cutting system controls with an improved height control.
Another object of the present invention is to provide new and improved cutting system controls that operate with virtually any plasma cutter and/or virtually any plasma torch.
Another object of the present invention is to provide new and improved cutting system controls that improve the operation of virtually any plasma cutter.